Monday
January 26, 2015

# Homework Help: Science: Chemistry

chemistry
How many kilowatt-hours of energy are necessary to heat the air in the house from 9∘C to 30∘C? The heat capacity of air is 1.03 J/g∘C.A room contains 45kg of air.
Friday, September 12, 2014 at 6:16pm

chemistry
Calculate the final temperature of 30mL of ethanol initially at 15∘C upon absorption of 913J of heat. (density of ethanol =0.789 g/mL)
Friday, September 12, 2014 at 6:13pm

Chemistry 1300
1) Aluminum metal reacts with chlorine gas to form solid aluminum trichloride, AlCl3. What mass of chlorine gas (Cl2) is needed to react completely with 163 g of aluminum? 2) Magnesium (used in the manufacture of light alloys) reacts with iron(III) chloride to form magnesium ...
Friday, September 12, 2014 at 4:36pm

Chemistry
3. The Haber–Bosch process for fixation of nitrogen is one of the more important chemical reactions ever invented. Without the invention of this process, which is used to make ammonia for fertilizer, the world’s population would not be as large as it is today. N2(g...
Friday, September 12, 2014 at 4:34pm

Chemistry, Help!
a) A 750-mL sample of hydrogen exerts a pressure of 822 torr at 325 K. What pressure does it exert if the temperature is raised to 475 K at constant volume? b) Aluminum oxide, Al2O3, is used as a filler for paints and varnishes as well as in the manufacture of electrical ...
Friday, September 12, 2014 at 4:32pm

chemistry
The density of pure copper is 8.96 at 20°C. If 6.50 g of pure copper pellets is added to a graduated cylinder containing 13.4 mL of water, to what volume level will the water in the cylinder rise
Friday, September 12, 2014 at 4:20pm

organic chemistry
or perhaps comparable over the counter?
Friday, September 12, 2014 at 11:06am

organic chemistry
Can a person be able to find some 1-Pentanamine (Y = NH2 over the counter ?
Friday, September 12, 2014 at 11:03am

chemistry
when 21.6g of carbon were burned in the presence of 73.9g of oxygen 16.3g of oxygen remain unreacted. What mass of carbon dioxide was produced
Friday, September 12, 2014 at 8:59am

CHEMISTRY
How do the indicators work , by changing color ?
Friday, September 12, 2014 at 6:21am

CHEMISTRY
How can we determine the equivalence point ( or end point ) in the curves in titration ( strong acid/weak base and weak acid/strong base )
Friday, September 12, 2014 at 12:36am

Complete each calculation. Express your answer to the correct number of significant digits. a)4.02mL + 3.76mL +0.95mL b)(2.7 x 10^2m) x (4.23 x 10^2m) c)5092kg divided by 23L d) 2-6.3 + 6-7 e)(6.853 x 10^3L) + (5.40 x 10^3mL) f)(572.3g + 794.1g) divided (24mL + 52mL) My ...
Thursday, September 11, 2014 at 9:20pm

chemistry
solution of 0.1molar NH4OH and 0.1 NH4CL ph=9.25 calculate kb for NH4OH?
Thursday, September 11, 2014 at 9:13pm

Chemistry
A 5 oz carrot is burned in a calorimeter containing 10.0 lb of water. The water heats up from 20.5 oC to 22.8 oC. How many Calories are in the 5 oz carrot? Round to correct sig. fig. 1 Cal = 1000 cal.
Thursday, September 11, 2014 at 9:11pm

Chemistry
A frozen dinner contains 1.5 g of fat, 14 g of carbohydrates, and 11 g of protein. How much energy is contained in this meal? Food energy Carbohydrate 4kcal/g Fat 9kcal/g protein 4kcal/g
Thursday, September 11, 2014 at 9:10pm

Chemistry
If 155 J of energy is added to 18.5 g of silver, how much will the temperature rise? Silver Specific Heat= (0.235J/g deg C)
Thursday, September 11, 2014 at 9:08pm

Chemistry
If we heat a 10 g sample of gold and a 10 g sample of iron with 50 kJ of energy each, which will have the greatest change in temperature? gold specific heat= 0.129J/g degC) iron specific heat = (0.452 J/g degC)
Thursday, September 11, 2014 at 9:05pm

Chemistry
Complete each calculation. Express your answer to the correct number of significant digits. a)4.02mL + 3.76mL +0.95mL b)(2.7 x 10^2m) x (4.23 x 10^2m) c)5092kg divided by 23L d) 2-6.3 + 6-7 e)(6.853 x 10^3L) + (5.40 x 10^3mL) f)(572.3g + 794.1g) divided (24mL + 52mL) My ...
Thursday, September 11, 2014 at 8:17pm

chemistry :)
Write the formula for the polyatomic ion in NaNO 3. Write the formula for the polyatomic ion in Ag2CO3. Write the formula for the polyatomic ion in NaHCO3. Write the formula for the polyatomic ion in BaSO4
Thursday, September 11, 2014 at 8:04pm

college chemistry
Express the concentration of a 0.0620M aqueous solution of fluoride, F-, in mass percentage and in parts per million. assume the density of the solution is 1.00g/mL.
Thursday, September 11, 2014 at 7:29pm

chemistry
which of the following is true regarding the transition elements? A. Multiple oxidation states resulting from the involvement of d electrons in bonding is a characteristic of transition elements. B. Most transition elements have lower melting and boiling points than the main ...
Thursday, September 11, 2014 at 5:12pm

chemistry
If you have 0.833g of copper(II) sulfate, how many moles doo you have?
Thursday, September 11, 2014 at 2:08pm

CHEMISTRY
What is difference between equivalence point and end point in the titration ?
Thursday, September 11, 2014 at 11:28am

CHEMISTRY
What indicator is better in the following titrations : 1) strong acid/strong base a) methyl red (4.4 - 6.2 ) b) bromophenol blue (6.2 - 7.6 ) 2) strong acid/weak base a) methyl orange (3.1 - 4.4 ) b) bromophenol blue (3.0 - 4.6 ) 3) weak acid/strong a) phenolphthalein (8.0 - ...
Thursday, September 11, 2014 at 11:25am

CHEMISTRY
Determine the solvent and solute in the following : a) carat 14 gold b) gaseous drinking ( pepsi for ex.)
Thursday, September 11, 2014 at 11:18am

CHEMISTRY
Classify these mixtures to homogeneous and heterogeneous a) orange juice b) tap water ( home water )
Thursday, September 11, 2014 at 11:14am

Chemistry
If there are 0.625 g of NaCl left in a beaker that originally contained 75.0 mL of saltwater, what must have been the molar concentration of the original solution? The molar mass of NaCl is 58.44 g/mol.
Thursday, September 11, 2014 at 10:54am

chemistry
mercury has a specific gravity of 13.6.How many mL OF mercury have a mass of 0.35kg.
Thursday, September 11, 2014 at 9:44am

chemistry
Calculate the ÄHvap , in kJ/mol, for ethanol, given that the vapor pressure at 45.0°C is 155.0 torr. The normal boiling point of ethanol is 78°C. Express your answer to two decimal places.
Thursday, September 11, 2014 at 9:29am

104 ml of ethene, C2H4 is burned in 408 ml of oxygen, producing carbon dioxide and some liquid water. Some oxygen remain unreacted. Calculate the volume of carbon dioxide produced and the volume of oxygen remaining
Thursday, September 11, 2014 at 7:06am

Chemistry - dilutions
The concentration of stain in the bottle was 5% and you added 100 microliters of it to 9.9ml of a buffer to make a working dilution of stain. You then combined 10 microliters of that diluted stain with 40 microliters of your diluted cells and put a few microliters of that ...
Thursday, September 11, 2014 at 2:18am

Chemistry
the current U.S. penny is only 2.5% copper the remaining portion is zinc. Given the density of copper as 8.94 g/cm and the density of zinc is 6.57 g/cm, calculate the density of a penny.
Thursday, September 11, 2014 at 12:23am

chemistry
If there are 0.561 g of NaCl left in a beaker that originally contained 75.0 mL of saltwater, what must have been the molar concentration of the original solution? The molar mass of NaCl is 58.44 g/mol. Give your answer to 3 decimal places
Wednesday, September 10, 2014 at 9:09pm

Chemistry
If the methane contained in 3.50L of a saturated solution at 25 ∘C was extracted and placed under STP conditions, what volume would it occupy? Solubility of methane is 1.3 millimolar
Wednesday, September 10, 2014 at 8:45pm

chemistry
a) Tetraphosphorus (P4), commonly known as white phosphorus, forms different compounds with chlorine (Cl2) depending on the amount of chlorine present. If chlorine is limited, phosphorus trichloride (PCl3) is formed. If there is an excess of chlorine, phosphorus pentachloride...
Wednesday, September 10, 2014 at 8:02pm

chemistry
A system initially contains 0.100 mol each of the three species sealed in a 10.0 L container. The temp was raised to a temp where the equilibrium constant Kc, is 12.6 for PCl3(g) + Cl2(g)--> <-- PCl5(g) Calculate the equilibrium concentration of all species.
Wednesday, September 10, 2014 at 7:33pm

chemistry
A system initially contains 0.100 mol each of the three species sealed in a 10.0 L container. The temp was raised to a temp where the equilibrium constant Kc, is 12.6 for PCl3(g) + Cl2(g)--> <-- PCl5(g) Calculate the equilibrium concentration of all species.
Wednesday, September 10, 2014 at 7:29pm

Chemistry
a) Tetraphosphorus (P4), commonly known as white phosphorus, forms different compounds with chlorine (Cl2) depending on the amount of chlorine present. If chlorine is limited, phosphorus trichloride (PCl3) is formed. If there is an excess of chlorine, phosphorus pentachloride...
Wednesday, September 10, 2014 at 7:27pm

chemistry
A room contains 47kg of air. How many kilowatt-hours of energy are necessary to heat the air in the house from 7∘C to 26∘C? The heat capacity of air is 1.03 J/g∘C
Wednesday, September 10, 2014 at 7:06pm

chemistry
Calculate the final temperature of 34mL of ethanol initially at 13∘C upon absorption of 938J of heat. (density of ethanol =0.789 g/mL)
Wednesday, September 10, 2014 at 7:04pm

Chemistry
a) Tetraphosphorus (P4), commonly known as white phosphorus, forms different compounds with chlorine (Cl2) depending on the amount of chlorine present. If chlorine is limited, phosphorus trichloride (PCl3) is formed. If there is an excess of chlorine, phosphorus pentachloride...
Wednesday, September 10, 2014 at 6:15pm

Chemistry
a) Tetraphosphorus (P4), commonly known as white phosphorus, forms different compounds with chlorine (Cl2) depending on the amount of chlorine present. If chlorine is limited, phosphorus trichloride (PCl3) is formed. If there is an excess of chlorine, phosphorus pentachloride...
Wednesday, September 10, 2014 at 6:08pm

chemistry
Calculate the equilibrium concentrations of all three substances. Kc=1.7e-3 Q=3.6e-3 [NO]=0.0015 mol/L [O2]=0.025 mol/L [N2]=0.025 mol/L I cannot figure out the concentration for NO...please help! thank you!
Wednesday, September 10, 2014 at 5:39pm

chemistry
A 14.0 kg sample of lead is measured out at 4 degrees celcius what is the specific gravity of lead?
Wednesday, September 10, 2014 at 5:06pm

Chemistry
1. Imagine that you work at a company that prepares chemical solutions. You are asked to label a solution to sell to different customers. One customer is a hospital, another is a chemistry lab at a university, and a third is a physics lab at a university. You added 900 kg of ...
Wednesday, September 10, 2014 at 4:13pm

chemistry
2. A researcher is often required to prepare solutions in the lab. Typically, a lab provides a concentrated solution. This solution must be diluted to the proper concentration. Hydrochloric acid is a common stock solution that is typically purchased at 37.0% HCl concentration...
Wednesday, September 10, 2014 at 2:03pm

Chemistry
Why Mg2+ ion has smaller radius than Mg atom?
Wednesday, September 10, 2014 at 8:35am

chemistry
For the electrolysis of molten potassium bromide: (a) write the equation for the reaction at cathode. (b) write the equation for the reaction at anode. (c) write the equation for the overall reaction.
Wednesday, September 10, 2014 at 4:36am

chemistry
Calculate the volume of fuel needed for a flight if the jet fuel has a density of 0.803kg/L.First use dimensional analysis to convert liter to grams.Then substract to find how many kilograms need to be added.then convert this mass into liters,This is a dimensionalanalysis ...
Tuesday, September 9, 2014 at 10:02pm

Chemistry
Can you help me understand how to review the math definition... what "percentage" means. I need to know what the total mass of the mixture of 42 grams of apples and 96 grams of oranges. ANd what is the percentage of mass the apples are? Thank you.
Tuesday, September 9, 2014 at 9:48pm

Chemistry
What are the orbital used in the formation of [COCL4]^2- ?explain this..
Tuesday, September 9, 2014 at 9:23pm

chemistry
at 17.9 degrees celsus ethyl ether has a vapor pressure of 400 torr. What is the mole fraction of ethly ether in a solution which has a vapor pressure of 380 torr, if the solute is non-volatile at 17.9 degrees celsus?
Tuesday, September 9, 2014 at 7:37pm

chemistry
Calculate the volume of fuel needed for a flight if the jet fuel has a density of 0.803kg/L.First use dimensional analysis to convert liter to grams.Then substract to find how many kilograms need to be added.then convert this mass into liters
Tuesday, September 9, 2014 at 5:31pm

chemistry
what is the mass of oxygen in a 5.6 g sample of Al(NO3)3.
Tuesday, September 9, 2014 at 5:30pm

Chemistry, HELP!!
Write out a balanced equation for reaction of solid zinc with hydrochloric acid (HCl(aq)). Indicate all states of matter in your equation.
Tuesday, September 9, 2014 at 4:07pm

chemistry
Use chemical formulas to generate the stoichiometric factor needed to express the results of a gravimetric analysis in terms of the substance on the left if the weighting form is the substance on the right: Sought Weighted I Mg Mg2P2O7 II UO2 U3O6
Tuesday, September 9, 2014 at 12:26pm

chemistry
Calculate the solubility of barium iodate in a solution that results when 100 ml of 0.014 M barium chloride are mixed with 100 ml of 0.03 M potassium iodate.
Tuesday, September 9, 2014 at 12:24pm

chemistry
What is the minimum silver ion concentration required to initiate the precipitate of silver bromate from 0.01 M potassium bromate
Tuesday, September 9, 2014 at 12:22pm

chemistry
Tuesday, September 9, 2014 at 8:49am

chemistry
A 21.8603 g sample of impure magnesium carbonate was heated to complete decomposition according to the equation MgCO3(s) → MgO(s) + CO2(g). After the reaction was complete, the solid residue (consisting of MgO and the original impurities) had a mass of 18.7358 g. ...
Tuesday, September 9, 2014 at 1:29am

Chemistry
1.630 g of iron ore is dissolved in an acidic solution. This solution is titrated to a pink endpoint with 27.15 mL of a 0.020 M KMnO4 solution. a. How many moles of MnO4- ions were consumed? b. How many moles of Fe2+ were in the iron ore sample? c. What is the percent of iron ...
Monday, September 8, 2014 at 11:31pm

Chemistry
Ca(OH)2 + SO2 ----> CaSO3 + H2O Assuming that this process is only 80 % efficient, how much Ca(OH)2 would be required to remove 1000 grams of SO2?
Monday, September 8, 2014 at 11:28pm

chemistry
The specific heat of a certain type of metal is 0.128 J/(g·°C). What is the final temperature if 305 J of heat is added to 57.2 g of this metal initially at 20.0 °C?
Monday, September 8, 2014 at 10:28pm

Chemistry help
I need help on these last three problems. -do the following problems and express your answer in correct scientific notation.- 1. (10x10^6)/(2x10^2) 2. (9x10^-4)/(2x10^3) 3. (4x10^5)(7x10^-3)/(1.4x10^-6)
Monday, September 8, 2014 at 9:50pm

chemistry
The radius of a strontium atom is 215 pm. How many strontium atoms would have to be laid side by side to span a distance of 4.47 mm?
Monday, September 8, 2014 at 6:58pm

Chemistry
The standard free energy of activation of a reaction A is 73.4 kJ mol–1 (17.5 kcal mol–1) at 298 K. Reaction B is one million times faster than reaction A at the same temperature. The products of each reaction are 10.0 kJ mol–1 (2.39 kcal mol–1) more stable...
Monday, September 8, 2014 at 6:00pm

Chemistry
A reaction has a standard free-energy change of –12.40 kJ mol–1 (–2.964 kcal mol–1). Calculate the equilibrium constant for the reaction at 25 °C.
Monday, September 8, 2014 at 5:58pm

chemistry
You have a metal tank containing 74.0 moles of nitrogen gas at a pressure of 15.0 atm. If the pressure is measured at a temperature of 25.0 °C, then the volume of the tank must be ___ liters. (Round your answer to one decimal place and do not include units with the number.)
Monday, September 8, 2014 at 5:36pm

Chemistry
Name the property that each change depends on. Then classify the property as either chemical or physical. a) You separate a mixture of gravel and road salt by adding water to it b) Carbon dioxide gas freezes at a temperature of -78C
Monday, September 8, 2014 at 4:39pm

Chemistry 2
Pure nitrosyl bromide, NOBr at 0.762 M is placed into a sealed vessel and heated up to 400 K. When the system reaches equilibrium, it is found that 65.1% of the nitrosyl bromide has decomposed to nitrogen monoxide and bromine. Determine Kc for this reaction at 400 K: 2 NOBr(g...
Monday, September 8, 2014 at 4:05pm

Organic Chemistry
Rank the given compounds based on their relative Brønsted acidities. H-CH3 H-OH H-Cl H-F H-NH2
Monday, September 8, 2014 at 3:40pm

chemistry
at a temperature of 5 celsius, 21.5 mg of a non electrolyte is dissolved in enough water to make a 150.0 ml solution. the osmotic pressure of the solution is 0.200 atm. what is the molar mass of the substance dissolved
Monday, September 8, 2014 at 12:05pm

CHEMISTRY
lABEL THE VARIABLES IN THE EQUEATION BELOW WITH THE CORRECT UNIT RATE=k(A) UNITS: S-1, M, M-2 S-1, M.S-1, M.S, M-1S-1 WHAT IS RATE WHAT IS K WHAT IS A
Monday, September 8, 2014 at 4:51am

CHEMISTRY
LABLE THE VARIABLES IN THE EQUATION BELOW WITH THE CORRECT UNITS RATE=k(a)(b) UNITS M-2S-1, M, M.S-1, M-1S-1, S-1, M.S WHAT IS K WHAT IS A WHAT IS B
Monday, September 8, 2014 at 4:46am

chemistry
Express the rate of the reaction in terms of the change in concentration of each of the reactants and products. 2D(g)+3E(g)+F(g)>>>>2G(g) + H(g) when D is decreasing at 0.30 MOL/Ls, how fast is (H) increasing?
Monday, September 8, 2014 at 3:52am

chemistry
Archeologists can determine the age of artifacts made of wood or bone by measuring the amount of the radioactive slope 14C present in the object. The amount of isolope decreases in a first-ordrr process. If 12.8% of the original amount of 14C is present in a wooden tool at the...
Monday, September 8, 2014 at 2:40am

chemistry
What mass of cesium bromine must be added to a 0.500 liter of water (d=1.00 g/ml) to produce a 0.981m solution? what are the mole fraction and mass percent of CsBr?
Monday, September 8, 2014 at 2:25am

chemistry
calculate the molality, molarity, and mole fraction of NH3 in an 12.80 mass % aqueous solution (d=0.9651 g/ml)
Monday, September 8, 2014 at 2:18am

chemistry
A 6.0-ft person weighs 177lb. express this person's height in meters and weight in kilograms.
Sunday, September 7, 2014 at 11:59pm

Chemistry
Suppose you have two 100-{\rm mL} graduated cylinders. In each cylinder there is 58.5mL of water. You also have two cubes: One is lead, and the other is aluminum. Each cube measures 2.0cm on each side. After you carefully lower each cube into the water of its own cylinder, ...
Sunday, September 7, 2014 at 11:37pm

chemistry
if the average speed of a helium atom at a certain temperature is 1130. m/s, what is the speed in miles per hour? (1 mi =1609m)
Sunday, September 7, 2014 at 10:30pm

chemistry
convert 1.65 A(circle above the A) to nanometers (scientific notation)
Sunday, September 7, 2014 at 10:24pm

chemistry
convert 3.43 A(with circle above the A) to meters(scientific notation)
Sunday, September 7, 2014 at 10:22pm

chemistry
convert 140 amu to kilograms (scientific notation)
Sunday, September 7, 2014 at 10:14pm

chemistry
convert 278 amu to grams (scientific notation)
Sunday, September 7, 2014 at 10:10pm

chemistry
What is the wavelength λ of the photon that has been released by−2.05×10−18 J?
Sunday, September 7, 2014 at 9:38pm

chemistry
19.0 kg /0.036 m(3)(cube)=??
Sunday, September 7, 2014 at 9:05pm

Chemistry
carry out the following conversions.Enter your answer in scientific notation a)232 amu to grams (b)135 amu to kilograms (c)3.03 amu A to meters (d)3.19 A to nanometers
Sunday, September 7, 2014 at 8:48pm

chemistry
1.4602 cm x 2.488 cm x 10.399 cm =??
Sunday, September 7, 2014 at 8:42pm

chemistry
calculate the density of a solid if a cube meassuring 2.04cm on one side has a mass of 124g ......................g/cm3 calculate the mass of a cube the same substance measuring 7.97cm on one side enter your answer in scientific notaation ..................x10 g
Sunday, September 7, 2014 at 8:38pm

a level chemistry
two most abundant atmospheric gases react to a small extent at 298K in the presence of a catalyst to achieve dynamic equilibrium: N2(g) + O2(g) ->/<- 2NO(g) Kp= 0.30 Partial pressure of N2 and O2 = 0.78atm 1dm3 flask and equilibrium established after 30min. temperature ...
Sunday, September 7, 2014 at 8:03pm

Chemistry
How much energy in kilojoules is released when 25.0 g of ethanol (C2H5OH) vapor at 93.0 C is cooled to -10 C? Ethanol has mp = -114.1 oC, bp = 78.3 oC, ΔHvap = 38.56 kJ/mol, and ΔHfus = 4.93 kJ/mol. The molar heat capacity is 112.3 J/(K.mol) for the liquid and 65.6 J...
Sunday, September 7, 2014 at 7:56pm

Chemistry
A household receives a $155 electricity bill. The cost of electricity is$0.129/kWh.How much energy, in joules, did the household use?
Sunday, September 7, 2014 at 7:37pm

chemistry
which pairing below does not correctly match the scientist with the contribution to the understanding of the atom A. Proust and the realization that the elements of compounds are found in certain proportions by mass B. Thomson and the law of definite proportions. C. Dalton and...
Sunday, September 7, 2014 at 6:57pm

CHEMISTRY
Ch3CN(CH3)C2H5 is my kekule drawing ok? I drew it and uploaded a picture. oi61. tinypic . com/2vmztir.jpg
Sunday, September 7, 2014 at 4:02pm

Chemistry
NaHCO3 + HCl = NaCl + H2O + CO2 The there are .0489 moles of CO2, and HCL is 6M. find the amount of HCL in mL and the grams of NaHCO3
Sunday, September 7, 2014 at 3:59pm

Chemistry
59.0 mL of a 1.60 M solution is diluted to a total volume of 268 mL. A 134-mL portion of that solution is diluted by adding 111 mL of water. What is the final concentration? Assume the volumes are additive.
Sunday, September 7, 2014 at 2:50pm

Chemistry- urgent!
Perform the following operations and express the results in the correct number of significant digits or decimal places. Express all results in scientific notation. Please help me I'm so confused on how to do this!! 15. (1.71 x 10^6)(6.73 x 10^-8)/2.25 x 10 20. (533)(24) 21...
Sunday, September 7, 2014 at 12:57pm

chemistry
An ore contains Fe3O4 and no other iron. The iron in a 65.46 gram sample of the ore is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 37.9 grams. What was the percent Fe3O4 in the sample of ore? Answer in units of %
Sunday, September 7, 2014 at 9:25am

Chemistry (concentrations)
A liquid mixture has 12.6 parts per thousand of MgCl2 dissolved. Calculate the [Cl-] in ppt? Im stuck plz help!
Sunday, September 7, 2014 at 7:15am

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